Vulnerability · Published Aug 28, 2026 · Assigned by VulnCheck

CVE-2026-82021Hermes Agent 0.18.2 < 0.19.0 MCP Catalog Supply Chain RCE via Mutable Branch Reference

High 8.3

In plain English

A high-severity security flaw in hermes-agent from NousResearch. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities).

Severity (CVSS 3.1)8.3High

Exploit odds (30 days)0.3%top 72.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Hermes Agent 0.18.2 prior to 0.19.0 contains a supply chain vulnerability in its bundled MCP catalog that allows a remote attacker to execute arbitrary code by compromising a third-party upstream repository referenced via a mutable branch rather than a pinned commit SHA. An attacker who compromises the upstream repository can propagate malicious code to every host that installs the affected catalog entry, with no further action required by the operator.

Affected products (as reported)

Vendor	Product	Versions
NousResearch	hermes-agent	0.18.2 – before 0.19.02026.7.7.2 – before 2026.7.20

Weakness: CWE-494 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

References

Hermes Agent v2026.7.20 Release Notes release-notes
Pull Request issue-tracking, patch
Patch Commit patch
https://www.vulncheck.com/advisories/hermes-agent-mcp-catalog-supply-chain-rce-via-mutable-branch-reference third-party-advisory